In MALDI-TOF, what property is measured to identify bacteria or proteins?

In MALDI-TOF, what property is measured to identify bacteria or proteins?

• A. Color
• B. Fluorescence intensity
• C. Absorbance at 600 nm
• D. Mass-to-charge ratio

Answer: (D)

MALDI-TOF identifies organisms by measuring the mass-to-charge ratio of ionized proteins. The sample is mixed with a matrix and hit with a laser, which ionizes the proteins. These ions fly through a time-of-flight analyzer, and lighter ions reach the detector sooner than heavier ones. The resulting spectrum shows peaks at specific mass-to-charge values that form a unique protein fingerprint for the organism, which is then matched to a reference database to identify bacteria or proteins. The other options—color changes, fluorescence intensity, or absorbance at a specific wavelength—are not what MALDI-TOF measures.

MALDI-TOF identifies organisms by measuring the mass-to-charge ratio of ionized proteins. The sample is mixed with a matrix and hit with a laser, which ionizes the proteins. These ions fly through a time-of-flight analyzer, and lighter ions reach the detector sooner than heavier ones. The resulting spectrum shows peaks at specific mass-to-charge values that form a unique protein fingerprint for the organism, which is then matched to a reference database to identify bacteria or proteins. The other options—color changes, fluorescence intensity, or absorbance at a specific wavelength—are not what MALDI-TOF measures.